The present invention relates to nuclear power reactor fuel bundles and, in particular, an improved method and apparatus for assembling of such bundles.
In a typical nuclear power reactor, nuclear fission occurs within so-called "fuel rods" which are assembled in a parallel array into bundles, a multiplicity of which constitute the fuel core of a reactor. Heat from the nuclear fission reaction is taken up by a fluid (usually water) flowing along the outer surface of the rods. As the reactor operates, the fuel is gradually consumed and it is necessary at periodic intervals to replace the fuel. However, only a minor fraction of the fuel bundles are replaced at any one time, in order to avoid large variations in reactor operation. In the event of premature bundle failure or fuel inspection, it is necessary to remove the bundles and to disassemble them for repairs, replacement, or inspection of selected tubes. Thus, the bundles must be readily adapted to disassembly by remote means, since they become highly radioactive during the operation of the reactor. A number of methods have been shown in the prior art for securing nuclear power reactor fuel bundles. See for example U.S. Pat. No. 3,431,170 and copending application Ser. No. 294,213, filed Oct. 2, 1971, now U.S. Pat. No. 3,864,211 and assigned to the same assignee as the present application. Another mode of securing reactor fuel bundles in their assembled conditions is shown in prior copending application Ser. No. 273,161, now abandoned in favor of continuation application U.S. Ser. No. 400,734, filed Sept. 26, 1973 filed July 19, 1972, which is also assigned to the same assignee as the present application.
Many of the prior art devices require the disassembly of relatively small parts which is difficult to do by remote disassembly techniques. Any such locking system should be as simple as possible, not only to reduce the cost of providing the locking system, but also to simplify the need for special tools and complicated procedures for the subsequent disassembly and reassembly under remote control conditions. The possibility of losing such parts during remote disassembly makes it desirable to provide a locking system which need not be disassembled at any time after the initial assembly. The present invention accomplishes the foregoing objectives by providing a novel and simple, inexpensive means of assembling a nuclear reactor fuel bundle.